1. Field of the Invention
One embodiment of the present invention relates to a memory device or an electronic device including the memory device.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Another embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a power storage device, an imaging device, a memory device, a processor, an electronic device, a method for driving any of them, a method for manufacturing any of them, a method for testing any of them, and a system including any of them.
2. Description of the Related Art
In recent years, semiconductor devices such as central processing units (CPUs), memories, and sensors have been used in various electronic devices such as personal computers, smart phones, and digital cameras. The semiconductor devices have been improved to achieve miniaturization, lower power consumption, and other various objectives.
Specifically, electronic devices have been downsized, and as a result, miniaturization of semiconductor devices included in electronic devices has been demanded. In the case of a memory device, for example, a three-dimensional structure (a stacked-layer structure) is employed for a memory cell or a multi-level memory cell is used in the memory device.
It has been proposed that a transistor whose channel formation region is formed using an oxide semiconductor (hereinafter also referred to as an oxide semiconductor transistor or an OS transistor) is employed as a write transistor in such a memory cell. For example, Patent Document 1 discloses a memory cell that can retain data even in the situation in which electric power is not supplied, by including the OS transistor as a write transistor. A memory including an OS transistor can be used as a nonvolatile memory.